I inferred that from my experienc trying to do so, but
solved the problem by transferring the worksheet with the archived
data to an array and working  from there. This can be done without
directly opening the archive workbook. It is referenced via GetObject
and never shows as an open workbook  (it's hidden), but can be read
into the array -- all of which is fine with me. My routine  has no need
to write to the archive file.